1. Field of the Invention
This invention relates to an image forming unit and an image forming apparatus that incorporates the image forming unit.
2. Description of the Related Art
Electrophotographic image forming apparatus are known which include at least one image forming unit detachably mounted on the main body of the apparatus. The image forming unit includes, for example, a photoconductive drum on which an electrostatic latent image is formed, a charging roller that charges the photoconductive drum, a developing roller that develops the electrostatic latent image with toner, a supplying roller that supplies the toner to the developing roller, and a cleaning mechanism that cleans the surface of the photoconductive drum. These structural elements are assembled as an integral unit, and are driven in rotation during printing.
Japanese Patent Application Publication No. 2006-48018 discloses a developing unit that includes a photoconductor rotatably supported on first side frames, a developing roller rotatably supported on second side frames, and springs that are mounted on the first side frames and urges the photoconductor and the developing roller against each other.
In other words, the image forming unit according to Japanese Patent Application Publication No. 2006-48018 includes a first unit on which an image bearing body carrying an electrostatic latent image thereon is rotatably supported, a second unit on which a developer holding body that develops an electrostatic latent image is rotatably supported, and an urging member that is mounted on each longitudinal end portion of either the first unit or the second unit, the urging member urging one of the first unit and second unit against the other of the first unit and the second unit. A single urging member disposed on each longitudinal end portion of either the first unit or the second unit is not sufficient to urge the image bearing body and the developing body uniformly along their lengths.